Etiquette with two part-time jobs...?

Not sure how to phrase this question, but here it is...

Early last week I interviewed for two part-time jobs. At the end of last week, one of them hired me and I started working this Monday. I told them my days would be Mondays Wednesdays Fridays. I told them this because if the second job came through I would be working there Tuesday Thursday though I didn't tell the first job about the second job nor did I tell the second job about the first job.

Just a few hours ago I got a call from the second job and I got it. Won't meet up with her until Tuesday, but I'm afraid there's some sort of etiquette when it comes to this.

I'm leaning toward telling my second job that since we spoke last I got ANOTHER part-time job and I scheduled that one around this one. So my questions are..

(a) Should I do that?
(b) Should I also tell the first job?
(c) Is there any other things I should know about?

Also I haven't signed anything yet for either one. Soon though.

As long as you are working full time hours why not get one full time job so that you can get benefits?

a & b) You don't have to say when you got the job. Just refer to it as your other job.

Sometimes people with a full time job have a second part-time job. If anything, it's proof that you want to work. Often times, they'll work both jobs on some days.